Portable lifts are widely used in industry and construction for many lifting operations. The lift of the present invention is a hand-propelled and manually-powered lift, useful in lifting loads of the order of 500 to 1,000 pounds, although with heavier duty components, it can be used with greater loads. Lifts of this general type are disclosed in U.S. Pat. No. 3,957,137, entitled PORTABLE MATERIAL LIFT, issued to Howard H. Vermette; in U.S. Pat. No. 4,131,181, entitled PORTABLE LIFT, issued to Howard H. Vermette; and in U.S. Pat. No. 4,421,209, entitled LIFT APPARATUS and issued to Howard H. Vermette and Andrew H. Daugherty, the present inventor. All of these patents are assigned to the assignee of the present invention.
A telescoping lift is disclosed in U.S. Pat. No. 3,876,039. Commercial telescoping lifts are available from Genie Industries and described in the pamphlet entitled, "Genie Lifting Tools for the Construction Trades", 1984, available from Genie Industries, 18340 N.E. 76th St., P.O. Box 69, Redmond, Wash., 98073, and in the manual, "Operators Manual Series 75 Lift", May, 1985, published by Sumner Manufacturing Co., Inc., 2900 DeSoto, Houston, Tex., 77091.
Despite the acknowledged utility of such prior lifts, they are often difficult to handle or to move (e.g., through doorways or into a van), and they are often time-consuming to set up for use.